Characterization of Listeria monocytogenes from various sources by Random Amplified Polymorphic DNA (RAPD) and serotyping

Genetic diversity among Listeria monocytogenes isolates recovered from livestock food products (milk and meat products), vegetables and human clinical cases with bad obstetrics history were studied. A total of 259 samples were screened for isolation, identification and characterization of L. monocytogenes by serotyping PCR and RAPD profiling. In the present investigation, 11.1% prevalence of L. monocytogenes has been recorded. Of these, 5 (19.2%) isolates were from vegetables, 14 (17.5%) from milk, 2 (9.5%) from milk products, 3 (5.7%) from meat, 1 (8.3%) meat products and 4 (5.8%) from humans clinical cases with bad obstetrics history. Serotyping PCR study revealed presence of serotype 1/2b and 4b. RAPD profiling resulted into 5 clusters indicating five major patterns of L. monocytogenes. All clusters included the isolates from various sources. However, cluster 3 and 5 included isolates from human and milk origin, respectively. RAPD pattern 4 and 5 included the isolates belonging to 1/2b or 1/2b and 4b serovar, whereas, other pattern, included L. monocytogenes belonging to various serovars. Prevalence of L. monocytogenes in different food samples signifies its potential as food born pathogen and RAPD-PCR offers greater discrimination of strains.